Lu-Hf Isotope and Zircon U-Pb Geochronometry of Idanre Charnockite Southwestern Nigeria: Implications for Petrogenesis
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The research presents new information on Lu-Hf isotopic composition and zircon U-Pb age to explain the origin of Idanre charnockite in relation to granite plutonism in Nigeria. Field assessment showed intermix of granite and charnockite on a single outcrop in the neighbourhood of the study area suggesting contemporaneous formation of the 206 207 two rocks.The range of emplacement age of Idanre charnockite as revealed by Pb/ Pb age dating is 569 ~ 613 Ma 176 177 with a mean value 590.3 ± 5.3 Ma (MSWD = 0.82).Furthermore, Lu/ Hf isotopic ratio (range: 0.000416 ~ 176 177 0.000935), initial Hf/ Hf ratios (range: 0.281957 ~ 0.281984) and εHf(t) (range: -14.8 to -16.6) indicated that magma was derived from melting of crustal components. Two-stage model age tDM2 (range: 2400 ~ 2500) suggested that the magmatic fluid contain components that were separated from the primitive mantle during Neo-archean. Zircon morphology and Th/U ratio revealed that the charnockite had magmatic origin. The zircon U-Pb age coincided with Neoproterozoic (Pan-African) orogenic episode. The age of Idanre charnockite is comparable to granitoids and charnockite intrusive units located within and beyond Nigerian borders.
Publication Info:
Author: Akinola, O.O. , Ghani, A.A. and Talabi, A.O.
Volume: 57
Issue: March
Published By: Journal of Mining and Geology, 2024-03-01